A234517 Sequence of numbers from A234515 such that A234515(n) > A234515(k) for all k < n.

2, 4, 6, 12, 24, 36, 60, 72, 120, 180, 240, 360, 420, 480, 720, 840, 1260, 1680, 2520, 5040, 7560, 10080, 12600, 15120, 20160, 27720, 30240, 32760, 55440, 65520, 83160, 110880, 131040, 166320, 196560, 221760, 277200, 332640, 360360, 393120, 415800, 443520

Offset: 1

Author

Jaroslav Krizek, Jan 03 2014

Keywords

• nonn

Comments

A234515 = natural numbers n sorted by decreasing values of number k(n) = log_n(sigma(n)), where sigma(n) = A000203(n) = the sum of divisors of n.

Conjecture: sequence a(n) for n >= 4 is not the same as sequence of numbers from A234516 such that A234516(n) > A234516(k) for all k < n.

Crossrefs

Cf. A002182 (numbers n such that tau(n) > tau(k) for all k < n), A002473 (numbers whose prime divisors are all <= 7).

Cf. A234515, A234516, A234518, A234519, A234520, A234521, A234522, A234523, A234524.

Programs

PARI

lista(nn) = {v = vector(nn, n, if (n==1, 0, log(sigma(n))/log(n))); v = vecsort(v,,5); m = 0; for (n=1, #v, if (v[n] > m, m = v[n]; print1(m, ", ")););} \\ Michel Marcus, Dec 11 2014

Extensions

480 inserted and more terms from Michel Marcus, Dec 11 2014